Desorption processes: Supercritical fluid regeneration of modified clays

The main objective of this work is the study of the regeneration capacity of modified clays using carbon dioxide. These modified clays are used as organic compounds adsorbents. Modified clays were used to remove ethyl acetate from aqueous solutions. Structural changes on the montmorillonite clay after a treatment with quaternary amines were investigated. The experimental step was also done using a packed column with the clay contaminated by ethyl acetate and toluene. Different pressures and temperatures were employed, leading to different fluid conditions (gas, liquid and supercritical). The results obtained showed the influence of the density of the supercritical CO2 and of the organic modifier in the desorption process. These data were modeled with a simple model and with models of first and second orders. The better results were reached using the second-order model. This study allows the scale-up of the desorption process for the regeneration of solid matrices using supercritical fluids. The modified clay capacity as a pollutant attenuator remained almost unchanged after a regeneration cycle.